Sound box



Mar. 6, 1923.

' B. R. SABROOK SOUND Box v Filed May 2, 1919 Patented 'Main 6, 1921.3.

UNITE BAGSTER ROADS SEABROOK, OF WINNIPEG, MANITBA, CANADA, ASSIG-NOR,` BYy MESNE ASSIGNMENTS, T0 LYRADION MANUFACTURING COM'PANY, OF MISHA- WAKA, INDIAN., A CORPORATION 0F DEL 'WAR/E.

SOUND BOX.

Application filed May 2, 191e4 serial No. 294,292.v

T0 all fw from it may concern Be it known that I, BAGs'rnR ROADS SEA- BRoox, of the city of Vinnipeg, in the Provence of Manitoba, Canada, have invented certain new and useful Improvements in Sound Boxes, of which the following is the specification.

The invention relates toimprovements in sound boxes as used on talking and similar machines and the principal object of the invention is to provide a non-sound absorbing Sound box which will deliver the sound waves to the customary tone arm with great intensity and will not act to absorb a considerable proportion of the sound as occurs in the present sound boxes of which I am aware.

A further object of the invention is rto irnprove the suspension of the stylus bar.

With the above objects in view the invention consists essentially in the arrangement and construction of parts hereinafter more particularly described and later pointed out in the appended claim, reference being had to the accompanying drawing in which Fig. l represents a front view of the sound box.

Fig. 2 represents a vertical sectional view centrally through the same.

Fig. 3 represents a horizontal sectional view at X-X Fig. 1.

In the drawing like characters of reference indicate corresponding parts in the several figures.

1 represents an outer casing provided centrally at the rear with an outlet tubular opening 2 and having the front side screw threaded to receive an annular metallic screw ring 3. To the back of the casing I secure a metallic elbow 4f or ordinary form and provided with an outstanding attaching flange 5 which is connected to the back of the casing by fastening screws 6, there lbeing a rubber gasket or washer 7 inserted between the flange and the casing. The outlet 2 opens to the interio-r of the elbow.

On the entire inner face of the back wall 0f the casing 1, I apply a comparatively thick non-responsive, non-metallic `and nonabsorbing layer or coating 8. 'Io insure the rm holding of this composition, the casing may be roughened as indicated at 9, Fig. so that the roughening actually extends into the composition and gives a large adhering surface.

Directly in front of the layer of composition an annular paper-like. ring may be placed which is first saturated in shellac under pressure. Next to this or even in contact with the composition there is placed two elastic cushioning rings 11 and 12 between which I support the usual diaphragm 13 formed of anydesired material. The various parts and the diaphragm are held in place by the screw ring 3 which holds them securely in place between the inner face of this ring and the front face of the composition 8. 14 represents the stylus bar which has the inner endattached to the diaphragm and the outer end pivotally attached to the bridge 17 which extends outward from the casing. The fulcrum of the stylus bar at 18 and 19 has conical recesses at the ends thereof into which the conical ends of screws 15 and 16 are seated.

20 and 21 represent tension springs per- .manently secured by means of screws 22 and 23 to the stylus bar so as to project transversely of the stylus bar fulcrum. The free ends of the springs are provided with adjusting screws 24 and 25 which engage the underside of the casing and the bridge respectively and are provided with lock nuts 26. Obviously this mounting allows of the in and out swinging of the stylus bar as provided for by the pivot pins and of the restraining of the swinging movement dependent on the adjustment given the springs through the screws 24 and 25. The stylus or needle 27 is connected to the lower end of the stylus -bar by a setscrew 28 in the ordinary way.

When this sound box is in use the absorption of the sound by the wall of the sound box is reduced to a minimum owing to the application of the non-responsive composition provided on the inner face of 'the casing recess consequently the sound waves are delivered from the sound box through the elbow with great purity and truthfulness. VIt may be explained that in existing sound boxes with which I am familiar, the inner face of the metallic casing is directly exposed to the interiorof the sound box and through the reflection of sounds therefrom and the resulting interference, absorbs, or in other Words, subtracts a 'considerable portion of the purity of the sound produced in the box by the movement of the diaphragm. This is obviously detrimental to the delivery of the sound Waves from the sound box to the elboiiv and their subsequent progress into the attached tone arm.

What l claim as my invention is A sound box casing having a central opening therethrough and an annular flange projecting therefrom beyond said opening, a plurality of projections of the inner face of said casing, a plastic self-setting composition covering the said projections in a thick layer.

Bfiosriin Rollins sEaBRooK.

ln the presence of- G. S. ROXBURGH, K. B. VAKEFIEID.

Signed at lllinnipeg, this 26 day of April 

